1) It consolidates small trades in time, so you can see the how a particular trade moves the resulting "real" execution price.

2) It consolidates small orders in orderbooks - so you can see the resulting "real" offer

3) It visualizes time between trades - so you can estimate how long will it take for a small exchange to execute your trade

4) Trade prices, order books and time between trades are consolidated between exchanges, so you can see, for example, the best execution price for a block trade of 10000 BTC across all USD exchanges.

All data are separated into "bid" and "ask" sides to provide more details.

Charts are adjusted for desired trade volume when it makes sense. Let you, for example, want to trade 1000 BTC. Then price impact of one order of 20 BTC is small. However, the price impact of 100 orders 20 BTC each is large. If you want to trade a smaller amount, say 5 BTC, then small orders have a bigger impact.

The system takes this effect into account - so 3 of the 5 charts for each exchange can be adjusted for trades of 10, 100, 1000, 10000 or 100000 BTC. We figured out that this granularity is enough. Finer adjustments don't provide with better insights as charts weighted for 10 and 15 BTC are similar. However, 10 and 1000 differ a lot.

You can read more about how our charts are calculated and how they can help taking trade decisions on 'Why' tab and its sub-tabs.

Consolidated view adjusted for volume of 1000 BTC is free. Full access requires a subscription for 0.3 BTC a month or 0.5 BTC for two months. You can enable subscription for just 24h for 0.05 BTC.

My co-founder and I believe that micro-payments are the only fair business model. We wanted 0.1 BTC or less initially, but taking in account small potential user base, that won't be enough to buy us a pizza and coke off the earnings.

Bitcoin enforces financial freedom, and we think that affordable micro-payments without government interference are the key to large scale Bitcoin success. Asking for donations is a manifestation of weakness - it would mean we don't believe that our own product is useful for other people and that most of our clients will reward us voluntarily. Advertisements would mean that our visitors pay indirectly, by being conditioned into buying other goods and services and by disclosing their private habits to advertisement agencies. Conditioning and violation of privacy are against freedom so they are against Bitcoin so they are bad.

Seemingly free services always have hidden cost. For example, welfare and pensions mean that you rob your own children, as they will have to pay for them in the future. We want our visitors to pay directly and voluntarily, without hidden costs of any kind. If you only use a free part of our service - you don't pay.

You can still help us by spreading the word - use 'Social' tab to like, tweet, reddit, digg us. We are proud to be a part of Bitcoin economy - so help it grow. We plan to add more gadgets to the tab over time.

But if you find our work worthwhile - think of your subscription fee as buying us a slice of pizza and a coke every month to encourage us, so we can innovate freely and don't have to work for corporations or be tiny parts in state bureaucracy machines. There are not many Bitcoin users yet, we won't buy ourselves yachts and mansions - we only want feel the support and excitement of doing something that brings mankind closer to the free Bitcoin-based society.

Here is what you get with subscription:

Charts for today for btc-e and 100 BTC. You can also see all volume and exchange selectors enabled:

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A pattern in orderboooks on cryptox, probably caused by trading bots constantly changing their order price:

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Sparse activity on btcex. It took 16 hours to sell 100 BTC there, but buying activity of liquidity demanders is stronger:

1. It doesn't display an opportunity if there's too little volume offered at a pair of exchanges.

You can see our arbitrage table shrinking as you increase the volume. For example, only 3 exchanges have 10k BTC in their order books: btceUSD, cryptoxUSD and mtgoxUSD.

2. It displays market order execution prices for corresponding volume instead of best prices.

In most cases, very little volume is offered at the best price - so if MtGox ticker says 5.3, it doesn't mean that you can buy or sell 1000 coins at that price. Our arbitragecalculator accounts for that by going deeper in the orderbook than best price and displaying you the real volume weighted average price between several orderbook entries.

So you can see prices for arbitrage between mtgoxUSD and btceUSD (for example) varying with volume.

3. We extended the usual color coding from 2 to 4 colors:

- orange means there is positive price difference - you can buy low at one exchange and sell high at another one (but beware transaction fees and other commissions!)- yellow means there is no arbitrage and negative bid-ask price difference is less than 10% - that is, market is efficient.- white means there is no arbitrage but price difference is more than 10% - it means there is a market making opportunity, you can try to make money by putting limit orders at these two exchanges- black means there's not enough volume on one of the exchanges

The 10% threshold is based on our subjective feeling of illiquidity and is more or less arbitrary.

4. At the top of the table you see best available execution price for the lot. You can use the percentage as a measure of bitcoin markets efficiency. The square is usually orange - so best bid usually is higher than best ask because of inefficiencies! But it's rather hard to capitalize on this difference as it requires a complicated execution strategy and will probably be eaten by different fees.

The free version of arbitrage table is delayed by 6 hours - it shows quotes 6 hours from now. The paid version (available after you subscribe with a modest fee of 0.5 BTC a month) shows realtime quotes (fetched from exchanges using their orderbook API every 15 seconds and updated using web sockets just like the charts).

Also note, that these days arbitrage opportunities only happen during price swipes, so keep watching

You are absolutely right, having only OpenID is not enough. We wanted to get the service up and running as soon as the main framework is ready and stable enough. Thus we limited social login options to OpenID providers.

We are already working on adding non-OpenID social login providers Facebook, Twitter, Vkontakte and others.

We chose not to implement the usual password based login in addition to social login because it takes too much work to make password-based logins secure. OpenID is by design not vulnerable to user database theft, and allows users to use very secure authentication schemes if they wish - certificates, two-factor auth etc.

We are sorry for this inconvinience with your OpenID login attempt. We'll try and do our best to fix this embarassing problem asap Hope this will not make bad impression on you

As for the subscription price, it is 0.5 BTC per month and includes both arbitrage table and full set of charts. We'll make subscription fee more prominent. Thank you again for your feedback.

on arbitrage table:if I understand correct the numberseg:-5.xx -6.xx%means the first number is absolute amount in USD and the second in %, - but I think % is the most important number and therefore has to be big and bold or so?it will be a nice feature if the highest (1 or 2) number(s) in % is in another color and/or bold or major the colors are very confusing me...why don't you take the colors used in whole world in traffic lights (red, Yellow, green and perhaps white or black as the 4.)that is much more intuitive (orange is too much near red for me and means stop for me...)

on arbitrage table:if I understand correct the numberseg:-5.xx -6.xx%means the first number is absolute amount in USD and the second in %, - but I think % is the most important number and therefore has to be big and bold or so?it will be a nice feature if the highest (1 or 2) number(s) in % is in another color and/or bold or major the colors are very confusing me...why don't you take the colors used in whole world in traffic lights (red, Yellow, green and perhaps white or black as the 4.)that is much more intuitive (orange is too much near red for me and means stop for me...)

I hope this is constructive review for you thx

Hi, ewibit!

Thank you for your constructive attitude We really appriciate it Please be sure that your opinion is valuable for us. As opinion of all our active and would be customers

You are right there are plenty to be done to improve the service and to become mature and actually really useful.We wanted to assure you and all our customers and guests that we are working hard to make this improvement come true.

You are absolutely right about those terms. The documentation lacks their description. And we will fix this inconvinience with our planned next update which I hope come very soon.

But to clarify your question I can tell that we used fairly common abbreviations for the sake of simplicity and minimalism.

MKT usually means Market Order (http://en.wikipedia.org/wiki/MKT) . So the full name of the term '1000 BTC MKT Exec Price' reads - 1000 BTC Market Order Execution Price. This is exactly the price at which you actually can buy/sell 1000 BTC on a given exchange in one market order. The idea to calculate this parameter was primarily from the trading convinience point of view. We assume that it might be useful to know current market execution price in conjunction with certain voume than just best price without relevant volume.

VWAP stands for - Volume Weighted Average Price so label 'VWAP Last 1000 BTC Traded' answers the following question: What was the price of last 1000 BTC sold or bought respectively. Here we assume that it will be interesting to compare how different Market Order price to sell/buy 1000 BTC from actually traded last 1000 BTC on the current market. Last 1000 BTC sold or bought could be traded in one big chunk or in a lot of small 0.1-1.0 BTC trades. To tell at which price it was sold/bought we calculate average price of all last trades until the sum of those trades equals 1000 BTC. Thus we believe this allows us to use the term VWAP in this case.

As for the arbitrage table format you are also absolutely correct. It must be some how reworked. I can agree with you that percent is more relevant for analyzes and must be better and differently highlighted. Your suggestion about colors coding is also relevant. And please be sure we are carefully gathering all such suggestions from all our customers to collect as much as possible opinions. Then when critical mass of such data is collected we will be able to analyze it and make a decision what must be done here and there.Once more thank you.

From our side I can tell that before the release of this service we were very concentrated on wide variety of technical issues: such as stability of the service, performance issues, user accounts and payment processing. Interaction with exchanges orderbook and trading api. Collecting data in database and on and on and on... So we ask for your understanding that we choose to delay some questions and decided to solve them not optimally but from the simple aesthetics point of view.

Once more thank you for using our service and giving us your constructive opinion, it is very important for us.